Air flotation machine

ABSTRACT

An air flotation machine with a slit-type airlift features inclined baffle plates located in the chamber thereof in rows located on both sides of said airlift and adapted to guide the sliding-down material to pass along the length of the chamber towards the inlet of the slit-type airlift, the top edge of which is located above the froth overflow lip with the result that the material which slides down along the inclined baffle plates, is entrained by the airlift to be multiply fed onto the froth bed.

Uvarov et al.

[ June 11, 1974 AIR FLOTATION MACHINE 2,202,484 5/1940 Emery 209 170 2,790,506 4/1957 V Vact [76] Inventors: Jury Petmvch Uvamv, Qktyabrsky 3,434,596 3/1969 kii uemfi 209/170 x prospekt, 384, kv. 35., L ubertsy Moskovskoi oblasti; Rem Iosifovich FOREIGN PATENTS OR APPLICATIONS fi fi g i z y g p 253,695 1/1970 U.S.S.R 209/170 v. oscow, 0t 0 Primary Examiner-Frank W. Lutter {22] Filed: Nov. 3, 1971 Assistant Examiner-Ralph J. Hill pp No I95 161 Attorney, Agent, or FirmHolman & Stern [30] Foreign Application Priority Data f l fl T S I: If f A .23, 1970 U.S.S.R 1424477 man-011m It'll/P6 amt eatures pr inclined baffle plates located in the chamber thereof 52 us. c1....; 209/170 261/77 210/221 in rows located bOth Sides of Said airlift and [51] Int. Cl B:03d 1/26 adapted to guide the slidingdown material to pass [58] Field of Search 209M655 170 261/77. along the length of the chamber towards the inlet of 216/221 the slit-type airlift, the top edge of which is located above the froth overflow lip with the result that the [56] References Cited material which slides down along the inclined baffle plates, is entrained by the airlift to be multiply fed UNITED STATES PATENTS onto the froth bed 1,847,659 3/1932 Maclennan 209/170 2,145,269 1/1939 Munro et al. 209/170 7 Claims, 4 Drawing Figures PATENTEDJun 1 1 m4 SHEEI 2 BF 3 FIG. 2

AIR FLO'IATION MACHINE BACKGROUND OF THE INVENTION This invention relates to air flotation machines or cells used in mineral dressing, preferentially, that of minerals within wide size range.

An air flotation machine is known having a chamber for the pulp containing the material being dressed, and a bathmounted pulp aerator which is made essentially of a number of perforated tubes connected to a compressed-air source.

Such machines are suitable for dressing coarsegrained materials but for this purpose they should be cascade-arranged or use should be made of a number of extra pumps or pulp feeders. The pulp throughout capacity however of such machines is as low as m /hr per linear meter of the machine which fails to satisfy increased needs.

Also known in the art are air flotation machines, wherein a slit-type airlift is mounted along the length of the chamber thereof which raises and aerate the pulp, located on the opposite end walls of the machine are the pulp charging device and the pulp discharge device, and the froth overflow lip situated therebetween on the top portion of the side wall of the chamber. Additionally, provision is also made for the air separation box located above the slit-type airlift lengthwise the exit aperture thereof, and for the air distribution box with the tubes to feed air to the airlift entrance aperture.

Such machines, however, fail when used for dressing coarse-grained materials, whereby further disintegration of the material imposes extra cost upon the mate rial dressing process and increases the losses thereof.

SUMMARY OF THE INVENTION It is therefore an essential object of the present invention to provide an air flotation machine that would be capable of dressing materials within wide size-range which object is attained by to multiply feeding the sliding-down material onto the froth bed and providing a reliable and uniform air supply throughout the length of the slit-type airlift.

It is another object of the present invention to provide higher recovery percentage of the material being dressed.

One of the substantial objects of the present invention is to reduce the amount of auxiliary equipment involved in pulp transferring and the possibility of arranging the chambers of a machine at the same level.

A further object of the present invention is to provide the possibility of controlling the material sliding-down rate and the number of repeated passes thereof onto the froth bed. i

A still further object of the present invention is to ensure that the pulp discharged from the slit-type airlift be divided into two equal flows and that these be fed above the level of the overflow lip.

The object of the invention is accomplished by the provision of an air flotation machine, comprising a chamber for the pulp containing the material being dressed, the chamber having a pulp aerator, a slit-type airlift arranged along the length of the chamber, a pulp charging device and pulp discharge device, both being located on the opposite end walls of the chamber, a froth overflow lip located on the side wall of the chamber in the top portion thereof in between the pulp charging device and the pulp discharge device, an air separation box located above the slit-type airlift lengthwise the exit aperture thereof. and an air distribution box to feed air to the airlift entrance aperture. wherein. according to the invention provision is made for inclined baffle plates arranged in tandem and located beneath the pulp aerator, the plates directing the sliding down material lengthwise the chamber towards the airlift entrance aperture whose exit aperture is located above the froth overflow lip, with the result that the material sliding down along the inclined baffle plates is sucked by the airlift to be multiply fed onto the froth bed.

Such a machine is capable of dressing materials within wide size range. This is due to repeated passage onto the froth bed; it also increases the recovery percentage of useful material and is able to operate when the chambers thereof are arranged at the same level.

It is desirable that in an air flotation machine the inclined baffle plates be arranged in rows located on both sides of the slit-type airlift.

This increases the effective area of the chamber and enables the froth to discharge to the from both sides at the same time.

It is expedient that each of the inclined baffle plates be made tiltable about its horizontal axis which is square with the side walls of the slit-type airlift.

Swivelling of the baffle plates enables their tilt angle to be varied and, consequently, varies the sliding-down rate of coarse-grained material along the plates and, which is of most importance, the multiplicity of feedcycles of the material being dressed onto the froth bed.

It is possible to interconnect each of the inclined baffle plates of one row through an articulated joint with a pull-rod common to said row so that the tilt angle of all the baffle plates of the row is simultaneously changed.

It is likewise possible to provide a longitudinal verti cal splitter plate at the exit of the airlift aperture, arranged lengthwise its axis to divide the airlift exit aperture into two portions of an equiareal flow passage.

This will enable equivalent amounts of pulp discharged from the airlift to be fed to both sides thereof.

It is recommended that an air distribution box be provided beneath the airlift, this box having in its top portion an elongated slit adapted to be shut off by a stopper device and being coaxial with the airlift entrance aperture.

Such a position of the air-distribution box slit will enable coarse-grained material that slides off the baffle plates, to be more effectively sucked into the airlift entrance aperture throughout the length of the chamber.

It is reasonable that the stopper device be made as a damper arranged vertically in the slit of the airdistribution box and provided with lateral ports for the air to escape, and that the damper be connected through a rod to the spring-loaded diaphragm 0f the air jack.

Such a construction of the stopper device provides for an automatic shutoff of the air distribution box slit when the air feed ceases.

BRIEF DESCRIPTION OF THE DRAWINGS For the sake of clarity, described below is an exemplary embodiment of the machine as disclosed in the present invention with due reference to the accompanying drawings, wherein:

FIG. 1 is a fragmentarily broken-away side elevational view of an air flotation machine, according to the invention;

FIG. 2 is a sectionalized end-elevational view of the machine of FIG. 1;

FIG. 3 shows the bottom portion of same machine with part thereof broken away to illustrate a stopper device in the slit aperture of the air distribution box; and

FIG. 4 is a section taken along the line IVIV in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION Reference being now first directed to FIGS. 1 and 2, the air flotation machine of the invention has one or a plurality of chambers 1 arranged at the same level, wherein the material being dressed is recovered from the pulp. The top portion of the chamber 1 is rectangular-shaped, while its bottom portion is pyramidal in shape. Located on one of the end walls of the chamber 1 is a pulp charging device (the direction of pulp feed being indicated with arrows) whereas on the opposite end wall of the chamber at the bottom thereof is located a pulp discharge device 3. Provision is made for a froth overflow lip 4 located in between said devices in the top portion of each of the side walls of the chamber l. Arranged along the length of the chamber 1 is a slit-type airlift 5 on whose both sides is located a pulp aerator 6 which is in effect a number of perforated tubes connected to a source of compressed air (not shown in the Drawing). Provided above the slit-type airlift 5 and arranged along the length of the exit aperture thereof is an air-separation box 7 having deflectors 8, longitudinal slits 9 for the air to escape into the atmosphere and slits 10 to feed the pulp onto the froth bed.

Located likewise in the top portion of the airlift 5 lengthwise the longitudinal axis thereof is a vertical splitter plate 11 to divide the exit aperture of the airlift 5 into two portions of an equiareal flow passage. The splitter plate 11 is adapted to divide the pulp discharged from the airlift 5 into two equal flows directed to the chamber 1.

The top edge of the slit-type airlift 5 is arranged above the level of the froth overflow lip 4, each of the side walls of the air-lift being provided on the outside with curved baffles 12 to effect tangential feed of the pulp flows from the airlift 5 via the slits 10 onto the froth bed.

The bottom portion of the slit-type airlift 5 is enlarged for better pulp suction, provision being made for an air-distribution box 13 (FIGS. 3 and 4) located beneath the airlift and having in its top portion an endlong slit 14 adapted to be shut off by a stopper device 15. The slit 14 of the air-distribution box 13 is coaxial with the entrance aperture of the airlift 5.

The stopper device 15 is essentially a damper l6 vertically mounted in the slit 14 of the air-distribution box 13 and having lateral ports 17 for the air to escape, the damper being interconnected via a rod 18 to a springloaded diaphragm 19 of an air jack (FIG. 2).

The damper 16 and the top portion of the airdistribution box 13 are rubberized.

Provision is made for tandem-arranged inclined baffle plates 21 located beneath the pulp aerator 6 (FIGS. 1 and 2) and adapted to guide the sliding down material lengthwise the chamber 1 towards the entrance aperture of the airlift 5.

The baffle plates 21 are arranged in two rows located on both sides of the slit-type airlift 5. Each of the baffle plates is tiltable round its horizontal axis which is square with the side walls of the slit-type airlift 5. This is attained due to articulated-joint connection of each baffle plate 21 through a carrier 22 to the side wall of the chamber 1 and to a pull-rod 23 in such a manner that each of the baffle plates 21 of one row is articulated to the pull-rod 23 common to this row. the pullrod being adapted to simultaneously vary the tilt angle of the baffle plates of said row. The tilt angle variation of the baffle plates is provided for changing the rate of travel of coarse-grained material sliding down therealong and for varying the number of feeds (circulation cycles) of the material onto the froth bed through the slit-type airlift 5.

The air flotation machine of the invention operates as follows.

The pulp containing hydrophobic and hydrophilic coarse grains of the material being dressed, is fed into the chamber 1 of the machine by means of the charging device 2 which spreads the pulp in a uniform flow over the entire width of the chamber 1.

As a result, the finely divided particles of the material being dressed are entrained by the pulp flow to be carried therewith over the pulp aerator 6, air being fed from the perforated tubes of the aerator as air bubbles to saturate the pulp. The hydrophobic grains of the dressed material get stuck to the air bubbles to form a mineralized froth, whereas the hydrophilic and nonfloatable solids sink under gravity onto the inclined baffle plates and slide down therealong at a definite rate depending upon the tilt angle of the baffle plates. As the solids drop down, they get concentrated in the pyramidal portion of the chamber 1 and then are sucked into the entrance aperture of the airlift 5.

The pulp discharged from the airlift 5 is divided by the splitter plate 11 into two flows which are directed on both sides of the air-lift 5 to pass onto the pulp deflectors 8 with the result, that large air bubbles are destroyed and the evolved air escapes through the slit 10 of the airseparation chamber 7, while the aerated pulp runs down as a froth bed along the curved baffle 12 and through the slit to .get onto the pulp surface in the chamber 1.-

The relatively large hydrophobic solids of the material under dressing are retained in the froth bed and, together with the finely divided floating particles, they flow by gravity over the lip 4 or are forced out by the froth eliminator (not represented in the Drawing).

Non-floating and hydrophilic solids drop down again by gravity to get onto the baffle plates 21 located closer to the discharge end and arranged preferably parallel to one another at a tilt angle variable by the pull-rod 23.

Provision of the baffle plates 21 in the chamber 1 enables the non-floating and hydrophillic solids of the material being dressed to be repeatedly fed onto the froth bed, whereas the tiltability of the baffle plates to a preset angle makes it possible to regulate the load of the solid phase materials coming onto the froth bed. Thus, when the material slides down along the baffle plates at a steep angle, the multiplicity of the controlled separation cycles is increased, whereas at a gentle slope of the baffle plates the multiplicity is decreased. The pulp depleted in the useful component is discharged through the device 3.

Air is fed into the airlift 5 through the air-distribution box 13 when its damper 16 is somewhat raised and air is free to escape from the box 13 through the port 17 of the damper. In case of any pressure drop in the air jack 20 the spring-loaded diaphragm 19 exerts upon the rod 18 to actuate the damper 16 to move down, thereby shutting off the endlong slit 14 of the airdistribution box 13. Thus, when the machine is stopped the endlong slit 14 of the air-distribution box 13 is prevented from being clogged.

Tests have shown the herein-described air flotation machine to successfully operate on a material with a wide range of particle size. For example, potassium ores with particle size up to 4 mm, sulphide ores, up to 2 mm and coal, up to 13 mm have been dressed successfully, the lower size limit being within 5-10 microns.

Besides, the use of the machine considerably cuts down capital investments and increases recovery percentage of the useful component by 2-3 percent.

We claim:

1. An air flotation machine for mineral dressing, said machine comprising at least one pulp carrying chamber having end and side walls and adapted to separate undressed material fed thereto into two streams, a first stream composed substantially of coarse grained and hydrophillic material of non-floatable size and a second stream composed substantially of fined grained and hydrophobic material of floatable size; a pulp aerator means located in said chamber said aerator means forming a froth bed of mineral pulp containing therein material of said second stream type, moving along the length of the chamber; a pulp charging device located on one of said end walls of said chamber for feeding the undressed material thereto; a pulp discharge device located on the opposite end wall of said chamber with respect to said pulp charging device; a froth overflow lip located at the top of at least one side wall of said chamber in between said pulp charging and pulp discharge devices; a narrow slit-type air-lift located along the length of said chamber so that its top edge is above said froth overflow lip; a plurality of mutually adjustable downwardly narrowing inclined baffle plates arranged in tandem beneath said pulp aerator means and the froth bed so that during operation of the machine material of said second stream type remains in the froth bed moving along the chamber while material of said first stream type repeatedly falls under gravity from the froth bed and is slidably guided by said baffle plates along said chamber towards the inlet of said slit-type airlift to be sucked and aerated therein and multiply fed onto said froth bed.

2. An air flotation machine as claimed in claim 1, wherein said baffle plates are arranged in rows located on both sides of the slit-type airlift.

3. An air flotation machine as claimed in claim 1, wherein each of said inclined baffle plates is tiltable about its horizontal axis which is square with the side walls of said slit-type airlift.

4. An air flotation machine as claimed in claim 1, wherein each of said baffle plates of the same row is articulated to a pull-rod common to said row and adapted to simultaneously vary the tilt angle of the baffle plates of the row.

5. An air flotation machine as claimed in claim 1, wherein said airlift is provided with a vertical longitudinal splitter plate located in the top portion thereof along its longitudinal axis to divide the exit aperture of said airlift into two portions of an equiareal flow section.

6. An air flotation machine as claimed in claim 11, wherein provision is made beneath said slit-type airlift for an air distribution box having at its top a longitudinal slit shuttable by a stopper device, said slit being coaxial with the airlift entrance aperture.

7. An air flotation machine as claimed in claim 6, wherein the stopper device is essentially a damper with lateral ports for the air to escape, said damper being vertically mounted in the slit of the air-distribution box and rod-interconnected to a spring-loaded diaphragm located in the air cylinder of the air flotation machine *I 

1. An air flotation machine for mineral dressing, said machine comprising at least one pulp carrying chamber having end and side walls and adapted to separate undressed material fed thereto into two streams, a first stream composed substantially of coarse grained and hydrophillic material of non-floatable size and a second stream composed substantially of fined grained and hydrophobic material of floatable size; a pulp aerator means located in said chamber said aerator means Forming a froth bed of mineral pulp containing therein material of said second stream type, moving along the length of the chamber; a pulp charging device located on one of said end walls of said chamber for feeding the undressed material thereto; a pulp discharge device located on the opposite end wall of said chamber with respect to said pulp charging device; a froth overflow lip located at the top of at least one side wall of said chamber in between said pulp charging and pulp discharge devices; a narrow slit-type airlift located along the length of said chamber so that its top edge is above said froth overflow lip; a plurality of mutually adjustable downwardly narrowing inclined baffle plates arranged in tandem beneath said pulp aerator means and the froth bed so that during operation of the machine material of said second stream type remains in the froth bed moving along the chamber while material of said first stream type repeatedly falls under gravity from the froth bed and is slidably guided by said baffle plates along said chamber towards the inlet of said slit-type airlift to be sucked and aerated therein and multiply fed onto said froth bed.
 2. An air flotation machine as claimed in claim 1, wherein said baffle plates are arranged in rows located on both sides of the slit-type airlift.
 3. An air flotation machine as claimed in claim 1, wherein each of said inclined baffle plates is tiltable about its horizontal axis which is square with the side walls of said slit-type airlift.
 4. An air flotation machine as claimed in claim 1, wherein each of said baffle plates of the same row is articulated to a pull-rod common to said row and adapted to simultaneously vary the tilt angle of the baffle plates of the row.
 5. An air flotation machine as claimed in claim 1, wherein said airlift is provided with a vertical longitudinal splitter plate located in the top portion thereof along its longitudinal axis to divide the exit aperture of said airlift into two portions of an equiareal flow section.
 6. An air flotation machine as claimed in claim 1, wherein provision is made beneath said slit-type airlift for an air distribution box having at its top a longitudinal slit shuttable by a stopper device, said slit being coaxial with the airlift entrance aperture.
 7. An air flotation machine as claimed in claim 6, wherein the stopper device is essentially a damper with lateral ports for the air to escape, said damper being vertically mounted in the slit of the air-distribution box and rod-interconnected to a spring-loaded diaphragm located in the air cylinder of the air flotation machine. 